6.2: Week 6 pt 2

Question 1

Types of neuroimaging used in evaluation of common intracranial pathologies include?

Answer 1

CT, MRI, U/S in babies

Question 2

Describe normal anatomy on imaging

Answer 2

On non-contrasted CT head bone or blood = white
Air, water, CSF = dark
Metal causes streak artifact

Some calcifications (white) can be normal, and they increase with age

Question 3

In general, MRI is the study of choice for detecting and staging intracranial and spinal cord abnormalities. It is usually more sensitive than CT because of what 2 things?

Answer 3

superior contrast and
soft-tissue resolution.

Question 4

Head Trauma - CT:
1) What is the goal?
2) What does mass effect look like?
3) What does blood look like?

Answer 4

1) To determine if there is a life-threatening, treatable lesion
-looking for a) mass effect and b) blood.
2) Look for displacement of normal structures
3) Will be bright and settle in crevices or dependent structures

Question 5

Skull Fractures:
1) Where do they usually occur? What are some types?
2) What do they typically imply?
3) How do you look for these on CT?

Answer 5

1) Usually at point of impact; linear, depressed, or basilar fractures.
2) additional intracranial injury
3) need to use “bone windows”

Question 6

What are 3 situations in which you can suspect basilar Fxs?

Answer 6

1) air seen in the brain
2) fluid in the mastoid air cells or
3) an air-fluid level in the sphenoid sinus

Question 7

What must you look at for CT of facial fractures?

Answer 7

Must look at several contiguous images as to ensure visualization of the entire fracture

Question 8

What do orbital blow-out Fxs lead to?

Answer 8

leads to a fracture of the inferior orbital floor (into the maxillary sinus) or the medial wall of the orbit (into the ethmoid sinus)

Question 9

tripod fracture: What causes them? What is it?

Answer 9

Caused by blunt force to the cheek
separation of the zygoma from the remainder of the facial bones

Question 10

Tripod fracture: What bones are involved?

Answer 10

1) separation of the frontozygomatic suture,
2) fracture of the orbital floor,
3) and fracture of the lateral wall of the ipsilateral maxillary sinus

Question 11

What are the 4 types of intracranial hemorrhage?

Answer 11

• Epidural hematoma
• Subdural hematoma
• Intracerebral hemorrhage
• Subarachnoid hemorrhage

Question 12

Describe Epidural Hematomas

Answer 12

between the dura mater and the skull
Usually from blunt head trauma from an MVA
Almost all epidural hematomas have an associated temporal bone fracture
appear as a high density, biconvex, lens-shaped “mass” most often found in the temporoparietal region
Don’t cross suture
lines

Question 13

subarachnoid hemorrhage:
1) What causes them?
2) Where are they?
3) What can they lead to?

Answer 13

1) Usually from ruptured blood vessel
2) Occurs between the arachnoid and pia mater
3) Can cause intraventricular Hemorrhage

Question 14

Intracerebral Hematoma:
1) What are some causes?
2) What may be seen on CT?

Answer 14

1) Trauma/ shearing injury
Vascular disease or rupture
amyloid deposits
2) CT findings of intracerebral hemorrhage change over time and may not be immediately evident on the initial scan

Question 15

Intracerebral Hematoma: How can they manifest on CT?

Answer 15

By multiple areas of high attenuation hemorrhage within the brain parenchyma on CT.

Question 16

What is characterized by producing unconsciousness from the moment of injury?

Answer 16

Axonal injury

Question 17

Describe axonal injuries

Answer 17

Acceleration/deceleration forces diffusely injure axons deep to the cortex, producing unconsciousness from the moment of injury
responsible for the prolonged coma following head trauma
initial CT scan may be normal or underestimate the degree of injury.
CT findings may be similar to those described for intracerebral hemorrhage following head trauma.

Question 18

What are the most common causes of cerebral edema?

Answer 18

HTN, masses are most common causes

Question 19

Describe Cerebral edema on imaging

Answer 19

• There may be compression or obliteration of the normal sulci.
• The ventricles may be compressed

Question 20

Reasons for imaging strokes include?

Answer 20

1) to determine if there is another cause of the neurologic impairment (ex/ brain tumor)
2) to identify the presence of blood so as to distinguish ischemic from hemorrhagic stroke
3) to identify the infarct and characterize it.

Question 21

Descr imaging of strokes

Answer 21

acute strokes are initially imaged by obtaining a non-contrasted CT scan of the brain
CT findings may be present immediately after a hemorrhagic stroke and within hours after the onset of symptoms for ischemic stroke.

Question 22

____________ is more sensitive and relatively specific for detecting early infarction [stroke] with the capacity to detect changes within 20 to 30 minutes of the onset of the event

Answer 22

MRI

Question 23

Strokes: Describe imaging over time

Answer 23

CT findings will depend on the amount of time that has elapsed since the original event.
1) 12 to 24 hours: Indistinct area of low attenuation in a vascular distribution.
2) >24 hours: Better circumscribed lesion with mass effect that peaks at 3 to 5 days and usually disappears by 2 to 4 weeks

Question 24

Hemorrhage from stroke can occur where?

Answer 24

into the brain parenchyma or the subarachnoid space.

Question 25

What imaging do you use for hemorrhagic strokes?

Answer 25

CTA or MRA to pinpoint area of hemorrhage and possible deploy coil or clip to stop bleeding

Question 26

Ruptured aneurysms: 1) Causes? 2) What type bleeds more freq?

Answer 26

1) Hypertension and aging increase growth 2) Larger aneurysms bleed more frequently

Question 27

Describe ruptured aneurysms & their Sxs

Answer 27

“the worst headache of my life.” Upon rupture, blood usually enters the subarachnoid space. most aneurysms are detected by either CTA or MRA.

Question 28

T/F: Generally, the greatest concentration of blood on imaging indicates the most likely location of the ruptured aneurysm.

Answer 28

True

Question 29

What are some causes of Hydrocephalus?

Answer 29

1) Under absorption of CSF 2) Restriction of the outflow of CSF   3) Overproduction of CSF

Question 30

Normal Pressure Hydrocephalus: 1) What is it? 2) When does it occur? 3) How is it treated? 4) What is seen on imaging?

Answer 30

1) a form of communicating hydrocephalus 2) 60-70 y/o 3) Easy to treat with ventriculoperitoneal shunt 4) Enlarged ventricles, with normal or flattened sulci

Question 31

Cerebral Atrophy leads to loss of?

Answer 31

Both gray and white matter

Question 32

1) What make up 40% of all intracranial neoplasms? 2) What are the 3 most common?

Answer 32

1) Metastases 2) Lung Melanoma Breast

Question 33

Brain Tumors; metastases: 1) What is seen on imaging? 2) Are there multiple? 3) What do they look like on CT?

Answer 33

1) well-defined round masses near the gray-white junction. 2) Usually multiple but can be solitary. 3) They are typically hypodense or isodense on non-contrasted CT.

Question 34

1) What most common primary brain tumor (benign and malignant) and the most common extra-axial mass? 2) What age group? 3) What is seen on imaging?

Answer 34

1) Meningioma 2) Prefer middle-aged women 3) : on unenhanced CT most are hyperdense and about 20% may contain calcifications

Question 35

Meningioma: 1) What is seen on contrast CTs? 2) What may it induce?

Answer 35

1) On contrast-enhanced studies meningiomas markedly enhance. 2) May induce vasogenic edema

Question 36

Vestibular Schwannoma (Acoustic Neuroma): 1) Where do they occur? 2) Sxs?

Answer 36

1) along the course of the eighth cranial nerve within the internal auditory canal 2) Most frequent symptom is hearing loss, but they also produce tinnitus and disturbances in equilibrium.

Question 37

________________ is the most sensitive imaging study for detecting vestibular schwannomas

Answer 37

Contrast-enhanced MRI

Question 38

1) The most common demyelinating disease is what? 2) What are the Sxs? 3) What parts of the brain does it affect?

Answer 38

1) MS (Multiple Sclerosis) 2) Any neurologic function can be affected by the disease, some patients have mostly cognitive changes, whereas others present with ataxia, paresis, or visual symptoms 3) Characteristically affects myelinated (white matter) tracts with plaques

Question 39

1) Where is MS most commonly located? 2) What is the study of choice?

Answer 39

1) In the periventricular area, corpus callosum and optic nerves 2) MRI